The deal is Impax's first acquisition from Gamesa. Last year, Impax has bought a wind-power portfolio of around 100MW in France and Poland from Spanish renewable-energy company Eolia Renovables.
Impax bought Hamburg-based developer Epuron late last year. Epuron is constructing a 12MW project in Picardy and expects to start building another 100MW in France and Germany over the next six months.
Speaking about the Gamesa deal, Impax investment director Joe Berry said: "We are delighted to sign our first Gamesa windfarm acquisition, and hope to expand our co-operation in the future.
"La Souterraine is an excellent fit within Epuron’s fast-growing French portfolio, and another milestone for the company’s ‘buy and build’ strategy."